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Novel Photodynamic Cancer Therapy Agent and Biochemical Phosphate Sensor Based on Nanomaterials

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Date Issued:
2016
Abstract/Description:
Biochemical research and clinical studies have revolutionized the field of medicine in both diagnosis and therapy. Researchers in the field of biochemistry and biotechnology are using nanomaterials in different applications to develop devices and materials that offer benefits to both patients and the health care industry. These include biochemical sensors, enzyme encapsulation, biomarkers, and drug delivery improvements for the treatment of cancer. This dissertation focuses on investigating two biochemical aspects using nanomaterials; namely therapy and clinical diagnosis.For therapy purposes, Silica nanoparticles were used as drug delivery system to develop a new photodynamic cancer therapy agent photo-acid generator (PAG) that selectively induces necrotic cell death of cancer cells. The developed PAG is oxygen-independent and - when excited at specific wavelengths - drops the pH within the lysosome of cancer cells to produce apoptosis/necrosis. It was specifically designed for in vivo applications and conjugated with synthesized, highly monodispersed silica nanoparticles (Si NPs) functionalized with amine groups via amid links (SiN-NH-PAG). Additional Features include high photo-acid quantum yield, high one-photon (1PA) and two-photon absorption (2PA) with low fluorescence quantum yield. In vivo, confocal microscope studies with HCT-116 (Human colorectal carcinoma) cancer cells showed that photodynamic processes in the presence of PAG were completed under one- photon absorption (1PA) conditions. In these experiments, cells were imaged at 1 min intervals for a total of 4 hours with the aid of Differential Interference Contrast (DIC). Among the photodynamic therapy agents tested via cytotoxicity experiments with the MTS assay, (SiN-NH- PAG) showed the best efficiency to induce cell death. The increased effectiveness of the new agent is probably due to the large number of PAG groups present on the surface of Si NPs.iiLysosome colocalization indicates that PAGs are mainly built in lysosomes. The increase of acidic content inside the lysosome was demonstrated with the aid of the LysoSensor Green probe. The drop in the intralysosomal pH was approximately 0.3 units. This is a desirable outcome as most cells underwent necrosis at pH ? 4.4. For clinical diagnosis purposes, a biochemical sensor was developed for the analysis of phosphate ions in urine samples. Abnormal levels of inorganic phosphate in human urine samples are related to the development of certain types of cancers affecting several organs of the human body, including breast, pancreas, lung and thyroid. The new biochemical sensor is based on the fluorescence energy transfer between a lanthanide luminescent probe [Tb-EDTA]-1 and gold nanoparticles (Au NPs) capped with a Cetyltrimethylammonium bromide (CTAB) micelle. With this approach, it was possible to selectively determine inorganic phosphate (Pi) in urine samples at the micro-molar concentration level. Urine samples collected from healthy, non-smoking individuals showed no interference from concomitants usually found in human urine samples. The simplicity of analysis provides an approach well-suited for (")real-time(") monitoring of phosphate ions. Analysis time is made possible within approximately 10 min per sample.
Title: Novel Photodynamic Cancer Therapy Agent and Biochemical Phosphate Sensor Based on Nanomaterials.
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Name(s): Fadhel, Alaa, Author
Campiglia, Andres, Committee Chair
Belfield, Kevin, Committee CoChair
Harper, James, Committee Member
Koculi, Eda, Committee Member
Bhattacharya, Aniket, Committee Member
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2016
Publisher: University of Central Florida
Language(s): English
Abstract/Description: Biochemical research and clinical studies have revolutionized the field of medicine in both diagnosis and therapy. Researchers in the field of biochemistry and biotechnology are using nanomaterials in different applications to develop devices and materials that offer benefits to both patients and the health care industry. These include biochemical sensors, enzyme encapsulation, biomarkers, and drug delivery improvements for the treatment of cancer. This dissertation focuses on investigating two biochemical aspects using nanomaterials; namely therapy and clinical diagnosis.For therapy purposes, Silica nanoparticles were used as drug delivery system to develop a new photodynamic cancer therapy agent photo-acid generator (PAG) that selectively induces necrotic cell death of cancer cells. The developed PAG is oxygen-independent and - when excited at specific wavelengths - drops the pH within the lysosome of cancer cells to produce apoptosis/necrosis. It was specifically designed for in vivo applications and conjugated with synthesized, highly monodispersed silica nanoparticles (Si NPs) functionalized with amine groups via amid links (SiN-NH-PAG). Additional Features include high photo-acid quantum yield, high one-photon (1PA) and two-photon absorption (2PA) with low fluorescence quantum yield. In vivo, confocal microscope studies with HCT-116 (Human colorectal carcinoma) cancer cells showed that photodynamic processes in the presence of PAG were completed under one- photon absorption (1PA) conditions. In these experiments, cells were imaged at 1 min intervals for a total of 4 hours with the aid of Differential Interference Contrast (DIC). Among the photodynamic therapy agents tested via cytotoxicity experiments with the MTS assay, (SiN-NH- PAG) showed the best efficiency to induce cell death. The increased effectiveness of the new agent is probably due to the large number of PAG groups present on the surface of Si NPs.iiLysosome colocalization indicates that PAGs are mainly built in lysosomes. The increase of acidic content inside the lysosome was demonstrated with the aid of the LysoSensor Green probe. The drop in the intralysosomal pH was approximately 0.3 units. This is a desirable outcome as most cells underwent necrosis at pH ? 4.4. For clinical diagnosis purposes, a biochemical sensor was developed for the analysis of phosphate ions in urine samples. Abnormal levels of inorganic phosphate in human urine samples are related to the development of certain types of cancers affecting several organs of the human body, including breast, pancreas, lung and thyroid. The new biochemical sensor is based on the fluorescence energy transfer between a lanthanide luminescent probe [Tb-EDTA]-1 and gold nanoparticles (Au NPs) capped with a Cetyltrimethylammonium bromide (CTAB) micelle. With this approach, it was possible to selectively determine inorganic phosphate (Pi) in urine samples at the micro-molar concentration level. Urine samples collected from healthy, non-smoking individuals showed no interference from concomitants usually found in human urine samples. The simplicity of analysis provides an approach well-suited for (")real-time(") monitoring of phosphate ions. Analysis time is made possible within approximately 10 min per sample.
Identifier: CFE0006528 (IID), ucf:51384 (fedora)
Note(s): 2016-05-01
Ph.D.
Sciences, Chemistry
Doctoral
This record was generated from author submitted information.
Subject(s): photodynamic therapy -- photoacid generator -- Lysosomal pH drop -- biochemical sensor -- phosphate determination
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFE0006528
Restrictions on Access: campus 2017-11-15
Host Institution: UCF

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